The 58-year-old, who reached a career high ranking of 574 in 1990, succeeds Massimo Calvelli "with immediate effect" after the Italian stepped down in June following more than five years in the role.
"Since 2021, he has served as a player representative on the ATP board of directors," the statement said.
"Polo will oversee the ATP's global operations and continue to drive OneVision – a transformative plan designed to grow the sport, elevate fan engagement, and deliver long-term value for players, tournaments, and partners across the Tour."
He will lead the ATP alongside the organisation's Italian president Andrea Gaudenzi, who has been in office since 2020.
"Eno is a dynamic and accomplished leader who understands both the commercial landscape and the intricacies of professional tennis," said Gaudenzi in Wednesday's ATP statement.
Polo was born and raised in Kenya and represented the national team before embarking on an international business career which has landed him senior leadership roles at sports equipment manufacturer Nike, Italian football club Juventus, sandal manufacturer Havaianas and the Premier Padel circuit.
"Tennis is at a transformative moment as a global sport and business," said Eno. "The opportunity that lies ahead is immense."
Calvelli's departure was announced in April, just over two weeks after a union and several players launched a series of legal actions accusing the body of "financially exploiting" them.
The 20 or so players named in the legal action also complained about playing conditions - matches played in extreme heat, different balls from one tournament to another - and the lengthening of certain tournaments in an already busy calendar.